With the development of science and technology, the tablet electronic devices, such as tablets, smart phone, MP4 players, etc., are used widely. When people use these devices, they need the sound. However, the effect of the sound output by these tablet electronic devices is often poor, it is hard to meet the high quality requirement. Therefore, most of the time, when these tablet electronic devices are used, an external sound box is used to output audio. Especially to get a good audio effect, two separate speakers are often used to achieve stereo effect. At present, most stereo system are two separate speakers, when used, the two speakers are placed separately. But this stereo system is not portable. And when people use tablet electronic devices, especially to listen to the music or watch movies, if people hold the tablet electronic device for a long time with the hand, people will feel tired, sometimes if people have to do some other things, it is also inconvenient. Therefore a holder is usually needed to erect the tablet electronic device, to set hands free. If people add a holder to erect the tablet electronic device, when wanting to move the tablet electronic device, people have to move more than one devices, that is the holder and sound boxes, which is very inconvenient, and also is difficult to facilitate portability of the tablet electronic device.